Disaggregating Census Population Using Satellite Imagery: A Case Study of Itasy Region of Madagascar

A research talk presented at the #ecmn23 conference by Léo Lipovac from the French Institute for Demographic Studies (INED).
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Abstract
Since 1960, a decline in mortality coupled with a high birth rate has increased Africa’s population from 300 million to 1.3 billion. This strong growth is expected to continue and the population is expected to double by 2050. In line with the United Nations Sustainable Development Goals (SDGs), the issues of education, health and social protection of the inhabitants are now at the center of attention. In order to act on these social needs, knowledge of the population and its geographical distribution is necessary.
Many research teams have tried to link population estimates and satellite images over the past decades. Whether the methods are top-down or bottom-up, the results are often similar and take the form of a gridded mapping of the population. Instead of disaggregating census population counts into 100x100m tiles, we explore the idea of disaggregating population estimates to the level of built-up area in both rural and urban settings, as identified by the TeleCense project of Diginove.
TeleCense offers a characterization of built up areas from algorithms applied to earth observation data stemming from the European Union’s Copernicus program. The Sentinel 1&2 satellites deliver images of the desired geographical area every 6 days with a resolution of 10m. Through the TeleCense program, Diginove processes these satellite images in order to map built-up areas, geo-locate them, and provide their environmental characteristics.
We will build different models, on the basis of 2018 Madagascar census population counts and supplementary variables stemming from remote sensing and international databases. The Itasy region will be used as a case study and will illustrate how our method enables us to go from the
commune level estimates to built-up area estimates, providing detailed mapping of population settlements.